Antenna is an essential key component of mobile communication products, the radiation efficiency, directivity, bandwidth, impedance matching characteristic, size and cost of which will have a great influence on communication products. At the same time, the requirements of miniaturization, diversity, legerity and beauty for communication products is making antenna design become an art incorporating the requirements of miniaturization, bandwidth, radiation efficiency and low-cost into it.
China patent CN1519986A discloses a microstrip antenna capable of increasing frequency bandwidth, which allows radio frequency signal to pass through paths of different length on two edges of one planar radiation sheet by using the planar radiation sheet and a gap opened at the input terminal of the radiation sheet, so as to attain an increased frequency bandwidth. It has the advantage of being easy-fabricated.
China patent CN1945898A discloses an ultra-bandwidth antenna, having two electromagnetic materials at the connection of its microstrip and radiation sheet so as to increase bandwidth.
Neither the above two patents satisfies the requirements of the frequency bandwidth for wireless mobile communication products in multiple system formats, and the size of the antenna is big relative to its installation size in a handheld device.